@Alikat , I have the Pfaff 1475cd, I've had it from new, and I love it. I've not had the same proble as you with the Pfaff, but have had it happen with several of my old Singers. I can't remember exactly how I fixed it, but I believe it involved removing the hand wheel, not sure if you would be able to do that on the Pfaff...
If you take it for a service, you could ask them to have a look at the winding mechanism? Thinking on my feet, I wonder if there are any YouTube tutorials online... I'll have a look, and if I find one, I'll be back.
Jessie